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Published on April 12, 2019

Medical Marijuana – Hope or Hype?Medical marijuana - hope or hype?

Medical marijuana has been legal in Massachusetts since 2012 and is now legal in 33 states. The numbers have grown in the past year. Additionally, 10 states have legalized recreational marijuana, including Massachusetts.

Voters are making their preferences on the topic known, but what are the medical implications of these decisions? We asked primary care physician Miguel Prieto, MD, with Emerald Physicians in Bourne to share his thoughts on the possible benefits and risks.

What do the studies show?

Based on current medical studies and research, it's fair to summarize that they found the purported benefits of marijuana to be much smaller and weaker than are often reported, but so, too, are the purported risks. So, its bad news for the patient who actually wants it to help their cancer, cure glaucoma and be made fully healthy by marijuana, according to Dr. Prieto.

The Institute of Medicine was tasked with conducting a comprehensive review on the health effects of cannabis, and it issued a report, “The [2017] Current State of Evidence.” It started out with 24,000 sources; whittled it down to about 10,000 to produce this 468-page document.

Did the report find any benefits of medicinal marijuana?

According to Dr. Prieto, there are only three benefits they could find “substantial evidence” for. The first was as a treatment for chronic pain in adults age 25 and older, when compared to placebo.

"We don't have enough studies comparing cannabis vs. existing medications for pain control," he said.

The only other two benefits were for chemo-induced nausea and vomiting, and relieving self-reported muscle tightness in patients with MS. Even archetypal medical marijuana indications, like glaucoma, failed to live up to expectations, he said.

Despite popular belief to the contrary, extensive research over decades has documented that marijuana is not effective in the management of clinical glaucoma, a disease of increased pressure within the eyeball, he said. Cannabis does lower eye pressure, but only for about an hour. You'd have to smoke a dozen joints a day - and even if you did smoke those few thousand a year, your body gets used to it. And so, what little benefit there is disappears within a few months in most patients.

Are there any adverse side effects of long-term or heavy use of marijuana?

Conspicuously missing from the list of adverse side effects of long-term or heavy use is any mention of chronic obstructive pulmonary diseases, like emphysema, which you can get from smoking tobacco, Dr. Prieto said. And similarly, it doesn't look like smoking marijuana increases the risk of respiratory cancers, like lung cancer, or head and neck cancer - though cannabis may increase the risk of testicular cancer. There have been three studies so far on marijuana use and testicular cancer, appearing to increase risk about 50 percent but only, it seems, for those smoking once a week or more, or for 10 years or longer.

What was the overall conclusion of the report?

Basically, the study concluded that there simply isn't enough research, which leaves patients, healthcare professionals, and policy makers “without the evidence they need to make sound decisions,” Dr. Prieto said. The study further found that “This lack of evidence-based information poses a public health risk.”

Is there anything that both sides of the medical marijuana debate can agree on?

Both sides can agree on the need for definitive clinical research, Dr. Prieto said. Otherwise, “we're just left with anecdotes, blogs, and ads, which don't provide a sound basis for assessing the safety and efficacy of pharmacologic agents.”

Because cannabis is just a naturally occurring plant, and cannot be patented, the pharmaceutical industry has not invested in trials for cannabis, he said. “What we need are large clinical trials. Until then, we're all just going to be scratching our heads. But, where's the funding for the research going to come from?”

Is there any portion of the population that should absolutely never use marijuana?

Young people should never use it, Dr. Prieto said.

“The evidence shows that chronic marijuana use in brains less than 25 years old does carry significant irreversible changes. The hypocampus and the amygdala, the parts of the brain tied to emotions and your memory, they shrink significantly according to studies.

“When adults stop using it they don’t have any long-term problems that we know of so far. Those areas tend to grow back. But when they researched it up in adults less than 25 years old, 18 until 25, it does not. They also lose an average of about eight IQ points that they did not recover.

“With people 25 and older that used it, when they were using the cannabis the IQ dropped about two points and once they stopped using it all together it just went back to normal. It still causes impairment so it takes you longer to process information and you forget things,” he said.

Do you recommend medical marijuana to your patients?

“Based on the lack of large clinical trials and the lack of evidence on effectiveness and safety, I do not recommend use of cannabis to my patients until such data is available,” Dr. Prieto said.

Note: As of 5/1/2019, Emerald Physicians joined Medical Affiliates of Cape Cod (MACC), a division of primary and specialty care physicians from Cape Cod Healthcare.